Effects of estrous cycle stage and transport temperature of ovaries on in vitro maturation of canine oocytes

Unlike other domestic animals, in vitro maturation (IVM) of canine oocytes still has limited success. The present study investigated the effects of estrous cycle stage and transport temperature of ovaries on in vitro maturation of canine oocytes. The donor bitches were categorized into three groups based on stage of estrus cycle: follicular (proestrus or estrous), luteal (diestrus) and anestrus. One ovary of each pair collected from 39 mature bitches was transported in Phosphate Buffer Saline (PBS) at 4 °C while the other was transported at 37 °C. A total of 1138 Grade I COCs obtained from all ovaries were grouped and matured in modified synthetic oviduct fluid (mSOF) supplemented with follicle stimulating hormone (FSH), luteinizing hormone (LH), essential and non-essential amino acids at 38.5 °C in a humidified 5% CO₂, 5% O₂, and 90% N₂ atmosphere for 72 h. The nuclear maturation rates were evaluated by aceto–orcein staining.Oocytes harvested from follicular and luteal ovaries have a significantly higher maturation rates (MI + MII) than the oocytes from anestrual ovaries in the 37 °C group (p < 0.05). However, oocytes harvested from anestrual ovaries transported at 4 °C had the highest maturation (MI + MII) rate, and the difference between anestrual and luteal ovary groups was significant (p < 0.05). The oocytes from anestrual ovaries transported at 4 °C have significantly higher maturation rates than those transported at 37 °C (p < 0.0001). However, the transport temperature (37 or 4 °C) did not significantly affect the maturation (MI + MII) rates of oocytes harvested from the luteal (p = 0.61) and follicular (p = 0.48) stage ovaries.It can be concluded from this study that (1) both transport temperature and transport temperature × estrus cycle stage interaction effected the maturation rates, while estrus cycle stage alone did not, and (2) transporting canine ovaries at 4 °C can improve in vitro maturation rates in oocytes harvested from anestrous ovaries.     

Interplaying factors for the formation of photoswitchable β‐hairpins: the advantage of a flexible switch

A series of peptidomimetics intended to promote the β‐hairpin motif have been studied. Structural variations include a turn region with and without a photoswitchable chromophore, and strands with amino acid side chains supporting various degrees of interstrand interactions for hairpin stabilisation. The propensity of the compounds to form β‐hairpins was evaluated experimentally by NMR spectroscopy, translational self‐diffusion studies and CD spectroscopy. In the presence of hairpin stabilising interstrand interactions, the structurally flexible stilbene chromophore appeared to be well compatible with the imposed secondary structure. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd.     

Effects of acetazolamide on aerobic exercise capacity and pulmonary hemodynamics at high altitudes.

Aerobic exercise capacity is decreased at altitude because of combined decreases in arterial oxygenation and in cardiac output. Hypoxic pulmonary vasoconstriction could limit cardiac output in hypoxia. We tested the hypothesis that acetazolamide could improve exercise capacity at altitude by an increased arterial oxygenation and an inhibition of hypoxic pulmonary vasoconstriction. Resting and exercise pulmonary artery pressure (Ppa) and flow (Q) (Doppler echocardiography) and exercise capacity (cardiopulmonary exercise test) were determined at sea level, 10 days after arrival on the Bolivian altiplano, at Huayna Potosi (4,700 m), and again after the intake of 250 mg acetazolamide vs. a placebo three times a day for 24 h. Acetazolamide and placebo were administered double-blind and in a random sequence. Altitude shifted Ppa/Q plots to higher pressures and decreased maximum O(2) consumption ((.)Vo(2max)). Acetazolamide had no effect on Ppa/Q plots but increased arterial O(2) saturation at rest from 84 +/- 5 to 90 +/- 3% (P < 0.05) and at exercise from 79 +/- 6 to 83 +/- 4% (P < 0.05), and O(2) consumption at the anaerobic threshold (V-slope method) from 21 +/- 5 to 25 +/- 5 ml.min(-1).kg(-1) (P < 0.01). However, acetazolamide did not affect (.)Vo(2max) (from 31 +/- 6 to 29 +/- 7 ml.kg(-1).min(-1)), and the maximum respiratory exchange ratio decreased from 1.2 +/- 0.06 to 1.05 +/- 0.03 (P < 0.001). We conclude that acetazolamide does not affect maximum exercise capacity or pulmonary hemodynamics at high altitudes. Associated changes in the respiratory exchange ratio may be due to altered CO(2) production kinetics.     

Molecular monitoring of fungal communities in air samples by denaturing high‐performance liquid chromatography (D‐HPLC)

Aims: To describe a new molecular technique for the assessment of fungal diversity in the air. Methods and Results: Air samples were collected every week in a henhouse in France during a 15‐week period. After air sampling, the collecting membrane was diluted, and the liquid was used for subsequent cultivation and molecular analysis: PCR‐temperature temporal gradient electrophoresis (TTGE), which has already been used for the identification of fungal species in air samples and PCR‐denaturing high‐performance liquid chromatography (D‐HPLC), a new technique for the analysis of complex microbial populations. D‐HPLC profiles were reproducible from run‐to‐run, and several fungal organisms could be identified at the species level by sequencing. Conclusions: PCR‐D‐HPLC enabled the identification of fungal species (both Ascomycota and Basidiomycota) that may be encountered in air. The new technique allowed the detection of more fungal species than did the PCR‐TTGE technique. However, some fungal species were detected only by PCR‐TTGE, suggesting that PCR‐D‐HPLC and PCR‐TTGE are complementary. Significance and Impact of the Study: PCR‐D‐HPLC represents a considerable saving in time over currently available procedures for detection and identification of fungal organisms in air. However, the fungal diversity detected by PCR‐D‐HPLC or by PCR‐TTGE was lower than that revealed by culture.     

Year-to-year changes in expression of maternal effects in perennial plants

Although there are numerous examples of maternal effects in perennial plant species, studies usually follow the fate of progeny only in their juvenile stages or for one growing season. Here we experimentally demonstrate, for two perennial species, that maternal nutrient environments and disturbance histories affect progeny differently during their first two growing seasons.Whereas progeny of mothers that suffered nutrient insufficiency produced more spikes in the first season, they produced equal spikes in the second season when compared to progeny of mothers from benign conditions. The progeny of mothers that had been grown in nutrient-poor conditions grew longer leaves in their second year, when compared to progeny of mothers from nutrient-poor conditions that experienced severe disturbance (removal of all above-ground biomass) but this was not the case in their first year. Additionally, progeny of mothers that experienced severe disturbance and were grown in nutrient-poor conditions produced longer leaves when compared to progeny of disturbed mothers grown in nutrient-rich conditions in the second year but this pattern was not observed in first year of the study.The changing expression of maternal effects in our study showed the necessity of longer-term studies to identify the effects and to determine their roles in the ecology of perennial species. We also suggest possible mechanisms responsible for the observed patterns.     

Colonization of abandoned swimming pools by larval mosquitoes and their predators following Hurricane Katrina

Thousands of flooded swimming pools were abandoned in New Orleans following Hurricane Katrina and provided a natural experiment to examine colonization of a novel aquatic habitat by mosquito larvae and their aquatic predators. We conducted a randomized survey of flooded swimming pools in two neighborhoods in January 2006 and found that 64% contained mosquito larvae, 92% contained predatory invertebrates, and 47% contained fishes. We collected 12,379 immature mosquitoes representing five species, primarily Culiseta inornata, and secondarily, the arboviral vector Culex quinquefasciatus. Dragonfly nymphs in the families Aeshnidae and Libellulidae were the most common predatory invertebrates collected among a total of 32 non-mosquito invertebrate species. Eleven species of fishes were collected, with Gambusia affinis accounting for 76% of the catch. Diversity of fishes in swimming pools was positively correlated with proximity to a levee breach and the fish assemblage found in swimming pools was similar to that found along shorelines of Lake Pontchartrain and drainage canals that flooded the study area. Mosquito larvae were rare or absent from pools containing fishes; however, path analysis indicated that the presence of top predators or abundant competitors may somewhat mitigate the effect of Gambusia affinis on mosquito presence.     

Synthesis, properties and interaction with eukaryotic cells of alkylating derivatives of oligodeoxyribonucleotides containing cholesterol or phenazinium residue covalently bound to the 3'-terminus

Radioactive alkylating 5'-[32P]-[4-(N-2-chlorethyl)N-methylaminobenzyl]-5'-phospham ide decadeoxyribothymidilate derivatives containing either free hydroxyl group (reagent I), hydrophobic cholesterol residue (reagent II) or polyaromatic phenazinium residue (reagent III) at 3'-termini were synthesized. The products were purified by HPLC and used for oligonucleotide-directed alkylating of DNA in isolated rat liver nuclei, Krebs-2 ascite carcinoma cells and L-929 murine fibroblasts. The uptake of reagent II by the cells was two orders of magnitude higher than that of reagent I and III. Intracellular alkylation of DNA by reagent II both in isolated nuclei and in living cells was about one order of magnitude higher than in the case of reagent I. The presence of phenazinium at 3'-termini of the reagent III leads to a sufficient increase of the alkylation extent compared to reagent I despite a quite low extent of its uptake by the cells.